This invention is in the area of compounds, pharmaceutical compositions and methods for the treatment of inflammatory, cardiovascular and immune disorders. The compounds and compositions of the present invention exhibit these biological activities by acting as PAF receptor antagonists and/or by inhibiting the enzyme 5-lipoxygenase.
Platelet activating factor (PAF, 1-0-alkyl-2-acetyl-sn-glycerol-3-phosphorylcholine) is a potent inflammatory phospholipid mediator with a wide variety of biological activities. PAF is generated and released by monocytes, macrophages, polymorphonuclear leukocytes (PMNs), eosinophils, neutrophils, natural killer lymphocytes, platelets and endothelial cells, as well as by renal and cardiac tissues under appropriate immunological and non-immunological stimulation. PAF causes the aggregation and degranulation of platelets at very low concentrations. The potency (active at 10xe2x88x9212 to 10xe2x88x929 M), tissue level (picomoles) and short plasma half life (2-4 minutes) of PAF are similar to those of other lipid mediators such as thromboxane A2, prostaglandins, and leukotrienes.
While PAF mediates essential biological responses, it also appears to play a role in pathological immune and inflammatory responses. Many published studies have provided evidence for the involvement of PAF in human diseases, including arthritis, acute inflammation, asthma, endotoxic shock, pain, psoriasis, ophthalmic inflammation, ischemia, gastrointestinal ulceration, myocardial infarction, inflammatory bowel diseases, and acute respiratory distress syndrome. Animal models also demonstrate that PAF is produced or increased in certain pathological states. Thus, compounds and/or pharmaceutical compositions which act as PAF receptor antagonists will be useful in the treatment of these and other disease states in which excessive amounts of PAF are present.
Leukotrienes, like PAF, are potent local mediators, playing a major role in inflammatory and allergic responses, including arthritis, asthma, psoriasis, and thrombotic disease. Leukotrienes are straight chain eicosanoids produced by the oxidation of arachidonic acid by lipoxygenases. Arachidonic acid is oxidized by 5-lipoxygenase to the hydroperoxide 5-hydroperoxyeicosatetraenoic acid (5-HPETE), which is converted to leukotriene A4, which in turn can be converted to leukotriene B4, C4, or D4. The slow-reacting substance of anaphylaxis is now known to be a mixture of leukotrienes C4, D4, and E4, all of which are potent bronchoconstrictors. There has been a long established research effort to develop specific receptor antagonists or inhibitors of leukotriene biosynthesis, to prevent or minimize pathogenic inflammatory responses mediated by these compounds. As such, compounds and/or pharmaceutical compositions which inhibit the 5-lipoxygenase enzyme will be useful in the treatment of disease states in which excessive amounts of leukotrienes are present.
Given the significant number of pathological immune and inflammatory responses that are mediated by PAF and leukotrienes, there remains a need to identify new compounds and compositions that exhibit PAF receptor antagonistic activity and/or inhibit the enzyme 5-lipoxygenase (5-LO).
2,5-Diaryl tetrahydrothiophenes, tetrahydrofurans and 1,3-diaryl cyclopentanes depicted in Formula 1 are inhibitors of PAF and/or 5-LO. They can be used for the treatment of pathological immune, inflammatory or cardiovascular disorders. 
wherein: 
and wherein:
W is independently selected from the group consisting of: xe2x80x94AN(OM)C(O)N(R3)R4, xe2x80x94AN(R3)C(O)N(OM)R4, xe2x80x94AN(OM)C(O)R4, xe2x80x94AC(O)N(OM)R4, xe2x80x94N(OM)C(O)N(R3)R4, xe2x80x94N(R3)C(O)N(OM)R4, xe2x80x94N(OM)C(O)R4, xe2x80x94C(O)N(OM)R4, xe2x80x94S(O)nR3, xe2x80x94S(O)n,CH2C(O)A, xe2x80x94S(O)nxe2x80x94CH2CH(OH)A, and xe2x80x94C(O)NHA, X is O, S, S(O) CR5;
Y1, Y2 are independently selected from the group consisting of:
(a) hydrogen;
(b) lower alkyl, lower alkoxy, lower alkenyl, lower alkynyl, alkylaryl;
(c) xe2x80x94AN(OM)C(O)N(R3)R4, xe2x80x94AN (R3)C(O)N(OM)R4, xe2x80x94AN(OM)C(O)R4, xe2x80x94AC(O)N(OM)R4, xe2x80x94AN(R3)C(O)N(OM)R4, xe2x80x94C(O)N(OM)R4, and xe2x80x94C(O)NHR3;
wherein A is selected from the group consisting of substituted or unsubstituted lower alkyl, lower alkyl-alkoxy, -lower alkyl-heterocycle-lower alkyl-, specifically including xe2x80x94CH2-heterocycle-CH2xe2x80x94, wherein the heterocycle is preferably furan or pyridine, more preferably, wherein the alkyl substituents are in the 2 and 5 positions of the furan ring, or the 2 and 6 positions of the pyridine ring, lower alkenyl, lower alkynyl, alkaryl or aralkyl; M is selected from hydrogen, a pharmaceutically acceptable cation, and a metabolically cleavable leaving group; R1 and R2 are independently selected from hydrogen, lower alkyl, preferably lower alkyl of 1-6 carbon atoms, e.g., methyl, cyclopropyl-methyl, ethyl, isopropyl, butyl, pentyl and hexyl, as well as C3-8, cycloalkyl, for example, cyclopentyl, halo lower alkyl, especially C1-6 haloalkyl, for example, trifluoromethyl, halo, especially fluoro, xe2x80x94COOH; R3 and R4 are independently selected from the group consisting of hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkyl where one or more carbon atoms are replaced by S, N, or O, substituted or unsubstituted cycloalkyl of from 3 to 10 carbon atoms, substituted or unsubstituted cycloalkyl of from 3 to 10 carbon atoms, where one or more carbons are replaced by S, N, or O, preferably lower alkyl, alkenyl, preferably lower alkenyl, alkynyl, preferably lower alkynyl, aryl, preferably phenyl, aralkyl, preferably benzyl, alkaryl, preferably toluyl, C1-6 alkoxy-C1-10 alkyl, C1-6 alkylthio-C1-10 alkyl, C1-6 hydroxy-C1-6 alkyl, C1-6 carbonyl-C1-6 alkyl, C1-6 amino- C1-6 alkyl;
R5 is selected from the group consisting of:
(a) hydrogen,
(b) lower alkyl, lower alkenyl, lower alkynyl, alkaryl;
(c) xe2x80x94AN(OM)C(O)N(R3)R4, xe2x80x94AN(R3)C(O)N(OM)R4, xe2x80x94AN(OM)C(O)R4, xe2x80x94AC(O)N(OM)R4, xe2x80x94AC(O)N(OM)R4, xe2x80x94AS(O)nR3, xe2x80x94AS(O)nxe2x80x94CH2C(O)R3, xe2x80x94AS(O)nxe2x80x94CH2CH(OH)R3, xe2x80x94AC(O)NHR3,
wherein each n is independently 0, 1 or 2; A is selected from the group consisting of substituted or unsubstituted lower alkyl, lower alkoxy, lower alkenyl, lower alkynyl, alkaryl or aralkyl; M is selected from hydrogen, a pharmaceutically acceptable cation, or a metabolically cleavable leaving group.
Preferred compounds of Formula I have the following structure: 
wherein A, R3, and R4 are all independently selected from the groups as defined above, X is N or Cxe2x80x94OCH3 and n is as defined above, and pharmaceutically acceptable salts thereof.
More preferred compounds of Formula I have the following structure: 
wherein R3 and R4 are independently selected from the groups defined above, preferably R3 and R4 are independently selected from the preferred groups defined above; X is N or Cxe2x80x94OCH3 and m is 2-10, and pharmaceutically acceptable salts thereof. 
A. Description and Properties of the Preferred Compounds
The term alkyl, as used herein, unless otherwise specified, refers to a saturated straight, branched, or cyclic hydrocarbon of C1 to C10, and specifically includes methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl, cyclopentyl, isopentyl, neopentyl, hexyl, isohexyl, cyclohexyl, 3-methylpentyl, 2,2-dimethylbutyl, and 2,3-dimethylbutyl.
The term lower alkyl, as used herein, and unless otherwise specified, refers to a C1 to C6 saturated straight, branched, or cyclic (in the case of C5-6) hydrocarbon, and specifically includes methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl, cyclopentyl, isopentyl, neopentyl, hexyl, isohexyl, cyclohexyl, 3-methylpentyl, 2,2-dimethylbutyl, and 2,3-dimethylbutyl.
The term alkenyl, as referred to herein, and unless otherwise specified, refers to a straight, branched, or cyclic (in the case of C5-6) hydrocarbon of C2 to C10 with at least one double bond.
The term lower alkenyl, as referred to herein, and unless otherwise specified, refers to an alkenyl group of C2 to C6, and specifically includes vinyl and allyl.
The term lower alkylamino refers to an amino group that has one or two lower alkyl substituents.
The term alkynyl, as referred to herein, and unless otherwise specified, refers to a C2 to C10 straight or branched hydrocarbon with at least one triple bond.
The term lower alkynyl, as referred to herein, and unless otherwise specified, refers to a C2 to C6 alkynyl group, specifically including acetylenyl and propynyl.
The term aryl, as used herein, and unless otherwise specified, refers to phenyl or substituted phenyl, wherein the substituent is halo or lower alkyl.
The term halo, as used herein, includes fluoro, chloro, bromo, and iodo.
The term halo (alkyl, alkenyl, or alkynyl) refers to a (alkyl, alkenyl, or alkynyl) group in which at least one of the hydrogens in the group has been replaced with a halogen atom.
The term heterocycle or heteroaromatic, as used herein, refers to an aromatic moiety that includes at least one sulfur, oxygen, or nitrogen in the aromatic ring. Non-limiting examples are pyrryl, furyl, pyridyl, 1,2,4-thiadiazolyl, pyrimidyl, thienyl, isothiazolyl, imidazolyl, tetrazolyl, pyrazinyl, pyrimidyl, quinolyl, isoquinolyl, benzothienyl, isobenzofuryl, pyrazolyl, indolyl, purinyl, carbazolyl, benzimidazolyl, and isoxazolyl.
The term aralkyl refers to an aryl group with an alkyl substituent.
The term alkaryl refers to an alkyl group that has an aryl substituent.
The term substituted (e.g., substituted alkyl) refers to one or more substituent groups selected from the following: halogen, hydroxy, amino, C1-C6 alkylamino, C2-C15 dialkylamino, carbamoyl, C1-C6 N-alkylcarbamoyl, C2-C15 N,N-dialkylcarbamoyl, cyano, nitro, C2-C15 dialkylsulfamoyl, CF3, C1-C6 acyl, C1-C6 alkoxy, carboxy, C2-C6 carboxylic acid, carboxamido, allyl, thio, C1-C6 alkylthio, C1-C6 alkylsulfonyl, C1-C6 haloalkylsulfonyl, C1-C6 alkylsulfinyl, C1-C6 haloalkylsulfinyl, arylthio, C2-C6, haloalkoxy, and the like.
The term organic or inorganic anion refers to an organic or inorganic moiety that carries a negative charge and can be used as the negative portion of a salt.
The term xe2x80x9cpharmaceutically acceptable cationxe2x80x9d refers to an organic or inorganic moiety that carries a positive charge and that can be administered in association with a pharmaceutical agent, for example, as a countercation in a salt. Pharmaceutically acceptable cations are known to those of skill in the art, and include but are not limited to sodium, potassium, and quaternary amine.
The term xe2x80x9cmetabolically cleavable leaving groupxe2x80x9d refers to a moiety that can be cleaved in vivo from the molecule to which it is attached, and includes but is not limited to an organic or inorganic anion, a pharmaceutically acceptable cation, acyl (for example (alkyl)C(O), including acetyl, propionyl, and butyryl), alkyl, phosphate, sulfate and sulfonate.
The term pharmaceutically acceptable salts or complexes refers to salts or complexes that retain the desired biological activity of the above-identified compounds and exhibit minimal undesired toxicological effects.
The term PAF receptor antagonist refers to a compound that binds to a PAF receptor with a binding constant of 30 xcexcM or lower.
The term 5-lipoxygenase inhibitor refers to a compound that inhibits the enzyme at 30 xcexcM or lower in a broken call system.
The term pharmaceutically active derivative refers to any compound that upon administration to the recipient, is capable of providing directly or indirectly, the compounds disclosed herein.
Preferred 2,5-diaryl tetrahydrothiophenes, and tetrahydrofurans and 1,3-diaryl cyclopentanes of the present invention exhibit PAF receptor antagonist activity with an IC50 of from about 1 nM to about 1 xcexcM, and/or they inhibit the enzyme 5-lipoxygenase with an IC50 of from about 50 nM to about 10 xcexcM, or they have dual activity, and are thus useful in the treatment of mammals, including humans, who have immune, allergic or cardiovascular disorders that are mediated by PAF or products of 5-lipoxygenase.
B. Stereochemistry
The 2,5-diaryl tetrahydrofurans, tetrahydrothiophenes, and 1,3-cyclopentanes disclosed herein exhibit a number of stereochemical configurations. Carbon atoms 2 and 5 in the center ring are chiral, and thus the center ring exists at a minimum as a diastereomeric pair. Each diastereomer exists as a set of enantiomers. Therefore, based on the chiral C2 and C5 atoms alone, the compound is a mixture of four enantiomers. The present invention is thus directed to each of the separated enantiomers, as well as to all of the possible mixtures thereof.
If nonhydrogen substituents are located on carbon atoms 3 and 4 in the center ring, then the C3 and C4 atoms are also chiral, and can also exist as a diastereomeric pair, that is also a mixture of four enantiomers.
The R groups in the active compounds described herein can likewise include chiral carbons, and thus, optically active centers.
C. Pharmaceutical Compositions
Humans, equine, canine, bovine and other animals, and in particular, mammals, suffering from inflammatory diseases, and in particular, disorders mediated by PAF or products of 5-lipoxygenase can be treated by administering to the patient an effective amount of one or more of the above-identified compounds or a pharmaceutically acceptable derivative or salt thereof in a pharmaceutically acceptable carrier or diluent to reduce formation of oxygen radicals. The active materials can be administered by any appropriate route, for example, orally, parenterally, intravenously, intradermally, subcutaneously, or topically, in liquid, cream, gel or solid form.
The active compound is generally included in the pharmaceutically acceptable carrier or diluent in an amount sufficient to deliver to a patient a therapeutically effective amount without causing serious toxic effects in the patient treated. A preferred dose of the active compound for all of the above-mentioned conditions is in the range from about 0.01 to 300 mg/kg, preferably 0.1 to 100 mg/kg per day, more generally 0.5 to about 25 mg per kilogram body weight of the recipient per day. A typical topical dosage will range from 0.01-3% wt/wt in a suitable carrier. The effective dosage range of the pharmaceutically acceptable derivatives can be calculated based on the weight of the parent compound to be delivered. If the derivative exhibits activity in itself, the effective dosage can be estimated as above using the weight of the derivative, or by other means known to those skilled in the art.
The compound is conveniently administered in any suitable unit dosage form, including but not limited to one containing 1 to 3000 mg, preferably 5 to 500 mg of active ingredient per unit dosage form. An oral dosage of 25-250 mg is usually convenient.
The active ingredient should be administered to achieve peak plasma concentrations of the active compound of about 0.01-30 mM, preferably about 0.1-10 mM. This may be achieved, for example, by the intravenous injection of a solution or formulation of the active ingredient, optionally in saline, or an aqueous medium or administered as a bolus of the active ingredient.
The active compound or pharmaceutically acceptable derivatives or salts thereof can also be mixed with other active materials that do not impair the desired action, or with materials that supplement the desired action, such as antibiotics, antifungals, other anti-inflammatories, or antiviral compounds.
D. Biological Activity
A wide variety of biological assays have been used to evaluate the ability of a compound to act as a PAF receptor antagonist, including the ability of the compound to bind to PAF receptors, and the effect of the compound on various PAF mediated pathways. Any of these known assays can be used to confirm the ability of the compounds disclosed herein to act as PAF receptor antagonists.
For example, PAF is known to induce hemoconcentration and increased permeability of microcirculation leading to a decrease in plasma volume. PAF mediated acute circulatory collapse can be used as the basis of an assay to evaluate the ability of a compound to act as a PAF antagonist, by analyzing the effect of the compound on PAF induced decreased plasma volume in an animal model such as mouse.
Endotoxemia causes the release of chemical mediators including eicosanoids, PAF, and tumor necrosis factor (TNF) that stimulate a variety of physiologic responses including fever, hypotension, leukocytosis, and disturbances in glucose and lipid metabolism. Endotoxemia can result in severe shock and death. Endotoxin-induced mouse mortality is a useful animal model to evaluate the pharmacological effect of compounds on endotoxic shock.
A wide variety of biological assays have also been used to evaluate the ability of a compound to inhibit the enzyme 5-lipoxygenase. For example, a cytosol 5-lipoxygenase of rat basophilic leukemia cells (RBL) has been widely utilized in studies on leukotriene biosynthesis. Compounds that inhibit 5-lipoxygenase decrease the levels of leukotrienes.
Another biological assay used to evaluate the ability of a compound to inhibit the enzyme 5-lipoxygenase is based on the classic pharmacological model of inflammation induced by the topical application of arachidonic acid to the mouse ear. On application, arachidonic acid is converted by 5-lipoxygenass to various leukotrienes (and other mediators), which induce changes in blood flow, erythema, and increase vasodilation and vasopermeability. The resulting edema is measured by comparing the thickness of the treated ear to a control ear. Agents that inhibit 5-lipoxygenase reduce the edematous response, by lowering the amounts of biochemical mediators formed from arachidonic acid.
E. Syntheses of the Preferred Compounds
The 2,5-diaryl tetrahydrofurans and tetrahydrothiophenes disclosed herein can be prepared in a variety of ways known to those skilled in the art, including by methods disclosed by Biftu, et al. in U.S. Pat. Nos. 4,539,332, 4,757,084, 4,996,203 and 5,001,123, and European Patent Application Nos. 90306234.7, 90306235.4, and 89202593.3.
1,3-Diaryl cyclopentanes can be prepared using the procedure of Graham, et al. (1.3-Diaryl Cyclopentanes: A New Class of Potent PAF 5 Receptor Antagonists. 197th ACS National Meeting, Dallas, Tex., Apr. 9-14, 1989, Division of Medicinal Chemistry, poster no. 25 (abstract)), or by other known methods.
A general procedure for preparing a hydroxyurea is: 
wherein R is a 2,5-diaryl tetrahydrothiophene or tetrahydrofuran; 1,3-diaryl cyclopentane with or without a linking moiety, and Rxe2x80x2 is a moiety as defined in detail above.
General procedures for preparing reverse hydroxyureas are: 
A general procedure for preparing a hydroxamic acid is: 
A general procedure for preparing a reverse hydroxamic acid is: 
The following schemes (1-10) illustrate the preferred synthetic methods utilized herein. The examples which follow these schemes are reflective thereof. These examples are merely illustrative, and are not intended to limit the scope of the present invention. 